BANGKOK, Thailand — Anti-government demonstrators in Thailand vowed revenge today, a day after their blockade of Parliament triggered wild melees with police that left two people dead and more than 400 injured.

There was no sign of renewed street clashes between police and protesters from the People’s Alliance for Democracy, which wants sweeping electoral changes to prevent what it says are corrupt politicians exploiting the rural majority to stay in power.

Troops armed with batons and helmets guarded the Bangkok police headquarters near Parliament, while hundreds of workers swept the surrounding streets, which were littered with burned-out cars and debris from Tuesday’s rioting — Thailand’s worst political violence in more than 16 years.

At least five major confrontations left 423 protesters and 20 police wounded, medical authorities said. Two died in the violence.

Prime Minister Somchai Wongsawat sought to reassure foreign diplomats that his government was in control of the country, later telling reporters that he had justified the use of tear gas against protesters as the “international standard” for restoring civil order.

But leaders of the alliance said they would not give up their campaign to overturn the government.

“We will not negotiate with a man who has blood on his hands,” said protest leader Sondhi Limthongkul amid loud applause from thousands of protesters at the compound housing the prime minister’s office, which they have occupied for six weeks.

“I ask our brothers and sisters to be strong and turn your sorrow into anger so we can have our revenge,” Sondhi said, calling for supporters nationwide to join the campaign.

A day earlier, anti-government protesters besieged the legislature and trapped lawmakers inside for several hours as police outside fired countless volleys of tear gas trying to clear the area.

Both sides accuse the other of using vicious tactics in Tuesday’s clashes.

Somsak Kosaisuk, a protest leader, said the government used “weapons of war” against peaceful protesters in Tuesday’s violence.

Demonstrators accused police of using grenades, but authorities said they only fired tear gas. Questions have arisen over whether tear gas canisters could blow off limbs and toes and feet — some of the more gruesome injuries suffered by protesters.

An Associated Press photographer saw stun grenades being thrown into the crowds. He and other AP staffers suffered from tear gas inhalation, and one required hospital treatment for minor burns and cuts.

Protesters said their gathering was peaceful, but many used iron rods, slingshots, firecrackers and bottles to attack police. An AP Television News reporter saw at least three protesters carrying guns. Authorities said some protesters also had explosive devices.

An AP reporter saw two police inside the parliamentary compound who had been shot by unknown assailants. Three police officers were shot and one was stabbed with a flagpole.

The street fighting was the worst in Thailand since 1992, when the army killed dozens of pro-democracy demonstrators seeking the ouster of a military-backed government.

One analyst said the turmoil was far from over.

“There is no end game in sight,” said Ji Ungpakorn, a lecturer in political science at Bangkok’s Chulalongkorn University. “The alliance is unlikely to stop here because they would lose momentum.”

Somchai, who was sworn in Sept. 25, was the main target of protesters who had hoped to prevent him from delivering his maiden policy speech by blockading Parliament.

The violence heightened the political uncertainty that has gripped Thailand since early 2006, when large protests called for Thaksin Shinawatra, the tycoon-turned-prime minister, to step down for alleged corruption and abuse of power.

A September 2006 coup ousted Thaksin, who is now in exile in London to escape corruption charges.

Somchai is Thaksin’s brother-in-law, a family tie that makes him unacceptable to protesters.

The protest alliance, which includes royalists, wealthy and middle-class urban residents and union activists, claims Thailand’s electoral system is susceptible to vote-buying, and that the rural majority, — the Thaksin camp’s power base — is not sophisticated enough to cast ballots responsibly.

It advocates abandoning one-person, one-vote to allow some lawmakers to be chosen by professions and social groups, but has not explained how such a system would work and be free and fair.